It is often desirable, when using tools such as brushes or the like, to mechanise the operation of same, both from a labour saving point of view, and often to improve the performance of such tools by increasing the speed or optimising a particular movement of same. Such is the case, for example, with an electric toothbrush, mixer, polishers/buffer or the like. However, in mechanising the operation of such tools, it is often necessary to limit the type of movement that the tool or tool head can undergo, in particular to keep the overall size, weight and complexity of the device within reason, in order to be practical for everyday use as a handheld and self contained tool. This is particularly evident in the field of electric toothbrushes, which can provide improved cleaning capabilities, but usually have a relatively limited range of movement at the brush head, in order to satisfy the above mentioned criteria.
The applicants International patent application WO2008/125269 discloses a toothbrush, in particular a mechanical toothbrush more commonly known as an electric toothbrush, which includes a spherical brush head which is capable of undergoing at least first and second independent brushing motions in order to improve the overall brushing effectiveness.
A number of embodiments are disclosed which detail various methods of delivering the first and second independent brushing motions to the head, and which incorporate different drive mechanisms to transmit motion to the bristled head of the brush. However, as with any toothbrush, whether mechanically/electrically or manually operated, the bristle on the head will in time become worn or significantly deformed to the point of requiring replacement. In order to prolong the working life of the head, and in particular the drive mechanism, it is preferable if the drive mechanism can be substantially sealed from the ingress of water and other contaminants such as toothpaste, while optionally including and retaining a lubricant about the drive mechanism. In addition, for a product such as an electric toothbrush it is important that the head of the brush can be replaced, while retaining the body, which includes the motor, control circuitry, and other aspects of the brush. It is also important that the head can be replaced quickly and easily by the end user. In addition to providing for the quick and easy replacement of the head by the user, there are other issues to be addressed in designing and manufacturing an electric toothbrush. In particular the cost and complexity of manufacture must be kept relatively low in order to provide an economically viable product, for example by designing the product for convenience of assembly during production. As the toothbrush of WO2008/125269 has a more complex drive mechanism than a conventional electric toothbrush, these are greater challenges to overcome.
It is therefore an object of the present invention to overcome some of the above-mentioned problems of the prior art.